Method and device for filtering and damping vibrations

ABSTRACT

The invention relates to a device to filter and damp the vibrations between a first element subjected to an incident vibratory wave and a second element radiating a filtered vibratory wave. 
     This device comprises an interface structure to transfer vibratory energy constituted by at least one elastic component and at least one dissipative component attached in parallel to the elastic component to ensure the filtration and damping of the incident vibratory wave, the dissipative component being constituted by two separate rigid frames ensuring, punctually or continuously, deflection functions, if required, by a lever arm effect, amplification of the vibratory energies generated by the elastic components towards a dissipative material positioned between them, the dissipative component providing damping for the elastic component.

The technical sector of the present invention is that of thevibro-acoustic filtering and damping of vibrations of mechanical origintransmitted between two structures so as to mutually protect them fromtheir vibratory environment.

Any element or structure included in a mechanical system incorporating asource of vibrations of mechanical origin receives vibratory and/oracoustic excitations from the source, modified or even amplified by thedynamic response of each of the structural elements constituting thesystem.

To ensure the system's mechanical strength, the structures or elementsmust be connected together by fastenings that provide sufficient staticor dynamic rigidity.

To reduce the vibratory energy transmitted from one structure to anotherwhen these are mechanically connected, two known types of solution areused to date: filtering and damping.

The first solution consists in mechanically filtering the inputexcitations of the structure to be protected. The effectiveness of thefiltering system is intrinsically linked to the resonant frequency ofthe system under load: the lower the cut-off frequency, the moreeffective the system. However, this flexibility caused by a lowercut-off frequency, leads to great motion space under load, incompatiblewith the immediate environment and causing the premature wear of thesystem.

For this, filtering may be obtained by integrating flexible elastic(leaf spring, metallic or composite spring) or hydraulic-elastic (fluid)or hyper-elastic (elastomer, silicon, specific alloy) systems to theinterfaces of the structure to be protected.

Elastic suspension, despite its ensuring static and dynamic strengthwith potential vibratory and/or acoustic gains, has a very slightlydamped specific resonance, injecting at this resonating frequency,redhibitory levels in the structure to be protected (low frequencydisplacements or accelerations with respect to resonant modes).

Patents FR-2 674 590 and JP-2 658 887 describe hydraulic suspensionsconstituted by chambers filled with a viscous fluid communicating by anarrow channel. When the suspension is stressed by a shock or byvibrations inducing relative displacements, the fluid willpreferentially circulate towards one chamber or other depending on thedirection of excitation, with a laminating function that will convertthe vibratory energy into local heat. The incompressibility of the fluidimproves suspension strength and its circulation provides damping forthe stresses introduced. These suspensions are largely used in the carindustry, in particular to uncouple the chassis from the running gear.However, they only function over a single degree of freedom and theviscosity of the fluid does not ensure the effectiveness of thebehaviour over a wide frequency band. These suspension/damping systemsare reserved for very low frequency filtering.

Hyper-elastic suspensions are constituted by thick blocks of elastomericmaterials according to patents FR-2 704 612 or FR-2762564 for example.The flexibility of these suspensions is incompatible with the need forstatic and dynamic rigidity and thus implies the installation of limitstops. The behaviour of these systems, obligatorily tri-axial, iscomplex and even random, thereby limiting prediction of dimensioning.Moreover, their behaviour at high frequency deteriorates (structuralstiffening) effect beyond the cut-off frequency) and their materialarchitecture cannot cope with the levels injected (premature ageing)thereby imposing wide safety margins in their dimensioning.

To overcome these drawbacks, hyper-elastic suspension solutions areconstituted by alternating superimposed layers of damping material andmetal with or without limit stops. The leaf springs work by flexion(patent FR-2678221), by shearing (patent EP-0155209) or by buckling(patent FR-2672351) whilst ensuring a low cut-off frequency andmechanical strength. Given the architecture of the damping process(alternate layers of hyper-elastic and metallic materials), the dampingperformances are weak. Moreover, when the limit stop is stressed on thesingle degree of freedom, the stiffness increases suddenly andre-injects heavy vibratory levels into the structure.

Apart from filtering, to reduce the vibratory and acoustic annoyanceradiated by a mechanical structure, multiple known solutions are basedon the criteria of separating the resonant frequency of the structurefrom the excitation frequency by acting on the mass and stiffnessparameters.

One solution consists in increasing the mass of the structure bycovering the radiating surfaces with high density material (for examplebituminous products). This solution is relatively effective on the highfrequency band of the structure but deteriorates its performance at lowfrequency. Moreover, it causes a substantial increase in the volume andmass.

Another solution consists in increasing the stiffness of the structureso as to push the frequency of the resonant modes back beyond theexcitation spectrum. This objective is difficult to fulfil sincehyper-stiff structures are in all logic made heavier by the stiffeningsystems: the cost to performance ratio remains high. Moreover,resistance to wear is reduced because of the punctual concentrations ofstresses with the appearance of new resonant modes at high frequencies.This solution does not solve the problem of resonance at highfrequencies.

One type of solution introduces the notion of damping via prestressedviscoelastic materials. This solution enables structural vibrationswhich may form the origin of acoustic radiation to be dissipated, thanksto the radiating surface being covered with a sandwich ofviscoelastic/metallic film material. This solution induces an increasein mass for limited damping performances.

Lastly, one solution, such as defined in an international documentWO97/11451 filed by the applicant enables structural damping to besignificantly improved over a wide frequency band. This technology,judiciously fastened in parallel to the radiating surface of a structuresubjected to vibratory excitations, allows the vibratory waves to bediverted, amplified then converted from vibratory energy into anotherform of energy. The dissipation of energy thus generated in thestructure by the parallel device, enables substantial damping to beprovided over a great number of resonant modes with a limited impact onthe mass and stiffness of the structure.

This state of the art thus enables on the one hand so-called “series”solutions that provide static and dynamic strength whilst enabling thefiltering over a reduced low or high frequency band; and on the other,so-called “parallel” solutions ensuring a strong reduction in vibratoryresponses of the normal mode of the structures over a frequency.

Application WO-01/92754 describes a beam having a quite specificstructure intended to be inserted between a vibrating structure andfixed structure. As presented, its conformation implies strong staticand dynamic rigidity, incompatible with low frequency filtering anddamping.

Thus, there are no “series” technology solutions enabling all thefunctionalities mentioned above to be combined, that is to say strongdamping and functioning over a wide frequency band.

The aim of the present invention is to supply such a system.

The invention thus aims to enable filtering with strong damping of theamplifications at resonant frequencies between two structures.

The invention thus relates to a process to damp and filter the amplitudeof mechanically-originated vibrations of a structure to be uncoupled,wherein the incident vibratory wave is filtered associated with damping,by providing absorption of the filtered vibratory wave transmitted overthe frequencies and the mechanical load amplitude applied.

Advantageously, the process associates a series suspension in the formof a suspension assembly mounted in series between two elements of thestructure with a damping device mounted in parallel to the suspension.

Advantageously, the damping device is of the parallel type and has aninternal geometry able to provide a deflection, and if required also anamplification and location of the vibrations to ensure damping of thefiltered vibratory wave, and the series suspension at the same time hasa sufficiently rigid static support function, and dynamic filteringfunctions with variable characteristics depending on the level of theload to be applied to the structure.

The invention also relates to a device to filter and damp the vibrationsbetween a first element subjected to an incident vibratory wave and asecond element radiating a filtered vibratory wave, wherein it comprisesan interface structure to transfer vibratory energy constituted by atleast one elastic component and at least one dissipative componentattached in parallel to the elastic component to ensure the filtrationand damping of the incident vibratory wave, a frequency and themechanical load amplitude applied.

Advantageously, the interface structure comprises a plurality of elasticcomponents positioned in series between the two elements, and aplurality of dissipative components each attached in parallel to eachelastic component.

Advantageously again, the dissipative component is constituted by twoseparate rigid frames ensuring, punctually or continuously, deflectionfunctions, if required, by a lever arm effect, amplification of thevibratory energies generated by the elastic components towards adissipative material positioned between them, this dissipative componentproviding damping for the elastic component.

According to one embodiment, the dissipative component has a linearprofile and is constituted by an assembly of rigid aligned frames,attached by their bases to the elastic components and independent of oneanother such that their relative movements, corresponding to anamplification by lever arm effect of the vibratory response of theelastic component, are transmitted by their ends to a dissipativematerial onto which a continuous or discontinuous stress plate ismounted to transfer the vibratory energy to the frame assembly.

According to another embodiment, the dissipative component is rotationaland constituted by an assembly of rigid frames, spaced cyclically or notaround a central part, attached rigidly or not at one end to the elasticcomponent on the one hand and free at the other end so that the relativemovements of these frames are transmitted to the dissipative materials,and attached on the other hand to a continuous or discontinuous stressedplate able, through the dissipative materials, to ensure the retentionof the frame assembly.

According to yet another embodiment, the elastic component comprises anassembly of two rotational sub-assemblies having a continuous ordiscontinuous evolutive profile of the elastic leaf spring type, atleast one of whose ends has an evolutive contact surface, the assemblybeing completed by a zone in which the dissipative materials areinserted.

Advantageously, the elastic leaf springs have potentially non-linearstiffness conferred by their evolutive geometric profile to ensure agradual contact of the leaf spring with the matching profile of theother leaf spring, to provide the evolution of the filtering frequencyand a controlled relative motion space of the leaves according to thedynamic load applied.

According to yet another embodiment, the interface structure isrotational or not and is composed of an elastic leaf spring rigidlyconnected to the element and an elastic leaf spring rigidly connected tothe element, the springs being connected together at their free ends andwound around a ring, elastic or not, using layers of dissipativematerials, and coming into direct contact according to the dynamic loadapplied to ensure the non-linear filtering and damping function.

Advantageously, the elastic leaf springs have potentially non-linearstiffness thanks to their evolutive geometric profile and by the gradualcontact between the leaf springs whose profiles reciprocally match theirrespective admissible maximal deformation, to provide, depending on thedynamic load applied, the evolution of the frequency and a controlled oreven limited relative motion space of the elements.

Advantageously again, the dissipative material converts the vibratoryenergy into another form of energy, for example heat energy by frictionbetween materials or with viscoelastic materials, electrical energy withpiezoelectric materials, magnetic energy with magnetostrictivematerials, or any other form of energy.

Advantageously again, the elastic component has at least two dimensionsand may be formed by assemblies of beams, plane plates or more complexshapes and in that its elastic properties stem from elastic materials,metallic or not, homogeneous or not, isotropic or anisotropic.

One result of the present invention lies in the fact that the method forfiltering and damping the amplitude of vibration phenomena of mechanicalorigin, transmitted to and/or radiated by structures towards an elementor towards another part of a structure is notable in that it associatessupport, filtering and damping functions, a frequency and mechanicalload amplitude applied.

Another result of the present invention lies in the fact that the methodfor filtering and damping the amplitude of vibration phenomena ofmechanical origin, transmitted to and/or radiated by structures towardsan element or towards another part of a structure is notable in that itperforms a so-called “series” function by its association with aso-called “parallel” process, functioning over a frequency. In improvingit, this association extends its field of application.

Another result of the invention lies in the control of the non-linearityintroduced in the series structure and is notable in that it enables thecontrol of the admissible motion space, this according to the load to beapplied to this structure.

Another result of the invention lies in a process to build a so-calledseries suspension for any object or structure, based on the internalmultiplicity of the devices and notable in that this process allows thesuspension to be used along one or several degrees of freedom.

Another result of the invention lies in the association of a so-calledseries suspension for an object introducing non-linearities with theso-called parallel process notable in that it enables the performancesof both devices, strong damping, strong excitation load) in a smallvolume at a reduced mass.

Another result of the invention lies in the filtering by an elasticsuspension placed in series between the structures to be insulated whosepotentially non-linear flexibility enables the filtering function to bemaximised beyond its own resonant frequency.

Yet another result of the invention lies in the fact that the elasticsuspension enables the static retention of the load and the amplitudesof precise and limited dynamic movements over a frequency and excitationloads.

Yet another result of the invention lies in the fact that the elasticseries suspension ensures a deflection of the direction of the incidentvibratory wave towards a damping device positioned in parallel to thissuspension.

Yet another result of the invention lies in the capacity of the dampingdevice to provide structural damping in the elastic suspension and,because of this, damp its vibratory response.

Advantageously, the association of two structures with a damping deviceenables the vibratory energies associated with the incident wave to beconverted into another form of locally dissipated energy. The dampingproperties of the overall device thus produced are thus those of theassociated damping device. Upon this basis, the applicant has carriedout research in the aim of improving its previously developed paralleldamping devices which already provide strong damping of the vibratoryresponse of the resonant and deformation modes of the elastic suspensionin order to develop its performances within the scope of an associationwith a series device, thus enlarging the device's field of application.

The introduction of non-linearities and their control enables theelastic series suspension to limit the motion space of the suspendedelement in the case of strong excitation load and this withoutre-injecting either disturbances or shocks into the element.

The association of non-linearities with known parallel damping devicesis notable in that it improves the exploitation of its dampingproperties, namely for strong excitation loads.

The association of a non-linear series suspension with known paralleldamping devices is notable in that it enables suspension to be obtainedthat has good damping performances (strong damping, strong excitationload) in a restricted volume at a reduced weight.

The internal multiplicity of the damping devices and the non-linearitiesis notable in that it confers the good performance already mentioned tothe suspension and this along one or several degrees of freedom.

The internal geometry of the series suspension made with the mechanicalelements is notable in that the static positioning it ensures does notevolve over time as is the case for known series suspensions composed ofelastomer.

Other characteristics, particulars and results of the invention willbecome more apparent from the additional description following, given byway of illustration, with reference to the appended drawings, in which:

FIGS. 1 and 2 show a first embodiment of a material according to theinvention in configurations of vibratory wave levels transmitted,

FIGS. 3 a and 3 b show another embodiment of the device according to theinvention,

FIG. 4 illustrates the unidirectional damping principle according to theinvention,

FIGS. 5 to 7 show variants of the principle enabling bidirectionaldamping and dissipation,

FIG. 8 shows a view of another embodiment of a multidirectionaldissipative component,

FIG. 9 is a section AA of FIG. 8,

FIGS. 10 and 11 show another embodiment of the device according to theinvention, and

FIGS. 12 and 13 illustrate an extension of the concept enablingmultidirectional damping and dissipation.

To better illustrate the method and device according to the invention,the application of a wave will be considered that is of mechanicalorigin, vibratory, micro-vibratory or nano-vibratory in input by itsincident surface and a vibratory, potentially sound, wave in output byits radiating surface.

According to the dynamic behaviour of a material positioned between anincident and radiating surface the wave transmitted will be more or lessdamped. Thus, when the material has a “neutral” behaviour with respectto the excitation field, the incident wave is fully transmitted to theradiating surface. Inversely, the flexibility of the material maygenerate an increase in the radiating wave (over-voltage to systemresonance) before filtering becomes effective.

The invention aims at filtering the incident wave and damping thevibratory wave generated by the radiating surface of a materialconstituting an element subjected to vibrations of mechanical origin atthe incident surface. This material is composed of an association ofelastic and dissipative structures defining an interface structure totransfer vibratory energy.

A material with dissipative structure, is defined as a material whoseparticles generate loads which are not proportional to the relativedisplacements imposed on them and which do not give back all thedeformation energy transmitted.

According to the invention, the dissipative material can convertvibratory energy into heat energy thanks to its viscoelastic propertiesby friction between two structures or by any other mode.

According to the invention, the dissipative material can convertvibratory energy into electric energy thanks to its piezoelectric ormagnetostrictive properties.

FIGS. 1 and 2 show an assembly composed of a combination byjuxtaposition or superimposition or transversal or longitudinal nestingof pluridimensional geometric motifs making up a dissymmetricalanisotropic structure, which is to say having along any of its axessolid motifs, dissymmetrical or not, and dissymmetrical cavities or nondissymmetrical cavities, which act to disturb wave transmission whateverits original direction. The structure according to the presentdescription is a geometrical body entering into the composition of thestructure of the device and in the implementation of the process. Thisstructure has at least two dimensions and may be formed by assemblies ofbeams, straight or curved bars, solid volumes, plane plates, or morecomplex shapes, as will be described hereafter.

FIG. 1 schematises the principle retained to amplify the deformationswhich is based on the use of a strongly anisotropic material orstructure 10. The interface structure 10 is interposed between a firstelement 2 rigidly attached to a support (not shown) and a second element3 subjected to vibrations. This structure 10 is constituted by anassembly of elastic leaf springs 1 and dissipative components 7. Theseleaf springs 7 are given a geometry and orientation which pilots theevolution of stiffness non-linearity according to their elongation, andthese leaf springs 1 can be observed to have a part 9 attached toelement 3 and another part 11 attached to element 2. A damping device 7is installed on each spring constituted by two frames 4 and 5 whose freeends are joined with a dissipative structure 6.

Even though the system is fully bijective, for the purposes ofsimplification and for the remaining embodiments described hereafter,element 2 is designated as the element via which the incident vibratorywave is transmitted, and element 3 as the element transmitting theradiating vibratory wave.

When the load f1 transmitted by the wave Oi of vibratory origin isapplied, the springs deform deflecting the direction of the incidentvibratory direction by deforming according to a mechanism previouslyestablished on their own modal behaviour as shown by way of illustrationin FIG. 2. In parallel to each leaf spring, the damping device 7, thanksto the frames 4 and 5 judiciously positioned on each spring, enablesthese energies to be deflected and, if required, amplified. These arefinally transmitted in a privileged direction or directions through thedissipative structure 6 with the frames 4 and 5.

Under the action of the dynamic load and thanks to the potentialdeformation types of the leaf spring 1, function of their evolutiveprofile, the distribution of the vibratory energies and the level ofinternal constraints in the springs 1 and consequently their stiffnessare modified. Since this mechanism is established in advance, thedamping device 7, effective over a frequency applied, is thus alwaysable to dissipate these energies. In FIG. 1, where the deformation rateof the springs 1 is considered to be weak, the structure 10 issufficiently flexible to statically support element 3, limits its motionspace and filters the majority of the loads F1 at low or high frequency.In this case, the low or high frequency damping properties are used withslight deformation of the dissipative structure. In FIG. 2, under astrong dynamic load F2, the stiffness of the springs 1 is stronglyincreased with their deformation rate. The structure 10 is thusstiffened thereby limiting the motion space to the required level. Butunder the combined action of the dynamic mass of element 3, thisstructure remains flexible enough to filter low frequencies. In thiscase, the damping properties are used with slight deformation of thedissipative structure.

The stiffness properties, by extension of the strength and damping ofthe assembly thus remain respectively piloted and this whatever thelevel or frequency of the dynamic excitation, by those of the suspensionand dissipative structure.

With the anisotropic conformation presented above, it is thus possibleto create suspension whose stiffness is low at low frequency and with alow level of stressing and much greater when the loads applied aregreater. This strong non-linear geometry allows flexible suspensions tobe produced which are damped whilst integrating rigidity at a high levelof deformation. Limit stops for damping mounts are no longer required.Moreover, the abrupt variations in stiffness linked to mechanical limitstops (fixed stop) no longer exist. The shock phenomena limitingequipment service life are thus eliminated.

FIGS. 3 a and 3 b show sections of another embodiment of the inventionin the form of a structure 10 placed between the incident surface 11 ofelement 2 and a radiating surface 9 of element 3. The structure 10 isconstituted of two sub-assemblies 12 and 13 nested into one another atone of ends 17. At another end 15, sub-assembly 13 is partially caughtbetween the frames of sub-assembly 12 thanks to the dissipativecomponent 6. Between ends 15 and 17, elements 14 and 16 constituteelastic leaf springs of the interface structure. These springs 14 and 16respectively represent the central parts of sub-assemblies 12 and 13 andhave an evolutive profile section whose base is firmly attachedrespectively to the incident 11 and radiating 9 surfaces. This profilemay be continuous or discontinuous, axisymmetrical or dissymmetrical.

The adoption of an elastic leaf spring 14 or 16, for example made of acomposite material, such as glass or carbon fibres embedded in apolymerised synthetic matrix, enables mechanical properties to beobtained that are strongly anisotropic and resistant under heavy loads.

Links 15 and 17 between the sub-assemblies 12 and 13 enables the leafsprings to be prestressed in flexion, traction or torsion, such thatunder the effect of the weight of element 3, the system is in itsresting position in a functioning zone of average stiffness.

As a whole the dimensional characteristics and the materialsconstituting the springs 14 and 16 combine to intensify thenon-linearity of their behaviour according to the dynamic load applied.

When a dynamic load is transmitted between the incident 11 and radiating9 surfaces, the springs 14 and 16 deform according to differentpre-established mechanisms (flexion, buckling, torsion, traction, . . .) according to the excitation level and frequency. These differentdeformation modes induce a modification of the stiffness of the elasticmaterial. The natural frequency of springs 14 and 16 is thus modified,thereby enabling the filtering frequencies of the process to becontrolled and extended.

So as to improve the non-linear dynamic behaviour of the filteringelement, the base of sub-assembly 12 has a profile 18 at its end 17which has a potential contact surface with profile 19 of spring 16, bymoulding to the shape of the maximal deformation of the spring 16.Contact is not established when the deformation rate of the spring 16 isweak. Over a certain threshold, contact is initiated over a smallportion of the spring 16. The behaviour of the spring is thus slightlymodified. If the dynamic load increases, the contact surface graduallyincreases and the dynamic behaviour of the spring 16 is stronglydisturbed leading to a significant impact on the increase in stiffness.

The impact of such an input of non-linearity of the contact type enableshigh levels of dynamic load to be reached, be it at low or highfrequency, without any danger of damaging the device. The fact theprofile 18 of sub-assembly 12 matches the deformed state of the spring16 avoids any abrupt contact being made, contrary to known limit stops.

The disturbance of the wave transmission between the incident 11 andradiating 9 surfaces is deflected towards the damping device 15 in azone ensuring maximum relative rotations or displacements of the springsaccording to their deformation. The damping devices 15 caught between arigid part of sub-assembly 12 and the elastic spring 14 and 16 enablethe relative energies to be absorbed through a suitable link whetherrigid, rotoid, spherical or flexible along privileged directions.

As a whole the device assembly described fulfils the damping functionenabling functionalities of deflection, amplification and conversion ofenergy of vibratory and/or acoustic energies to be ensured.

Thus, in the application which has just been described, the dampingdevice 15 dissipates the energy of vibrations from the springs 14 and 16thanks to the addition of a viscoelastic material 6 in zones 15 wherethe energy of the vibratory wave is concentrated by the geometry of thismaterial. The structure of the material enables one or several degreesof freedom of the material to be deflected and privileged for whichviscoelastic damping is the most effective. The application of theinvention thus enables the energy of the incident vibratory wave to bedeflected in zones 15 of springs 14 and 16, and then dissipated inanother form in well defined zones 15 and in directions which implycertain vibration modes of mechanical origin of the radiating wall.

The internal properties of the composite material constituting the zone15 influence the vibratory response of springs 14 and 16 by damping itsvibrations. From that point, the process and device according to theinvention have sufficient functionalities to satisfy the needs forfiltering and damping required by the user.

According to the invention, the parallel damping device, used in theseries suspension or with any other structure may have differentprofiles or geometries, so long as the damping process and deviceaccording to the invention are respected. The simplest form is shown inFIG. 4, where the energy-converting material 6 may be arranged betweenthe two rigid plates 18 and 19 of the structure 7, itself linked to thespring 1 of any other vibrating element using the rigid plates 4 and 5,reference being made to the embodiment shown in FIG. 1. The privilegedconversion functioning mode corresponds to a deflection of the vibratoryenergies from the spring 1, amplified by elements 4 and 5, towardsplates 18 and 19, which transfer these energies to the dissipativematerial. In the case presented, dissipation is generated by a dynamicshearing of the material 6.

As soon as the vibratory energies require it, the process may integratean amplification functionality for the vibrations before they aretransmitted to plates 18 and 19 by facilitating the lever arm effect ofplates 4 and 5. This amplification may also be performed either by theinternal geometry of the series suspension itself or the structure onwhich the device is mounted in parallel, either by attaching it betweentwo non-contiguous points, providing sufficient differential fordisplacements or deformations.

By way of example, FIGS. 5, 6 and 7 show, non exhaustively, differentforms which the improved parallel damping device may be given to be usedin the series suspension or in any other structure.

FIG. 5 shows an embodiment 7 in which the frames 4 and 5 have a T-shapedprofile, connected at their base to springs 1 and between which at theirrespective ends the dissipative material 6 has been integrated.

FIGS. 6 and 7 show, non exhaustively, specific forms which can be givento the parallel damping device 7. The embodiments are obtained using anassembly of aligned rigid frames 44 and 45, attached at their base tospring 1 or to any other elastic structure having unjoined upper ends.At these ends, their relative movement corresponds to an amplificationby lever arm effect of the vibratory response from the elastic component1 and is transmitted to the lower surface of the dissipative material 6.The upper face of this dissipative material 6 is held in place by acontinuous or discontinuous rigid stress plate 8 a and 8 b. The relativedeformations to which the dissipative material is subjected, maximal onone side and nil on the other, enable a high level of vibratory energyto be efficiently converted.

In the embodiments shown in FIGS. 4, 5, 6 and 7, the deflection,amplification and conversion are performed by a so-called lineicimplementation of the devices in that they facilitate bidirectionaltreatment. Other forms of surface conditions are identified so long asthey enable multidirectional treatment.

Thus, a first surface form of the damping device presented in FIG. 12 isa variant on the dissipative component 7 mounted on element 1. Thecontinuous or discontinuous structure 50, constituted of an isotropicmaterial or not, homogeneous, aggregatory or composite, is rigidlyattached by its base 50 a to element 1 subjected to vibrations. Becauseof its material and geometric properties, the component 50 is given ajudicious stiffness to flexion and shearing to deflect, or amplify thevibratory energies of the radiating structure. Its upper end 50 b is initself flexible enough to deform like a membrane. These deformations area resultant of the deformations of vibrating element 1, amplified by thegeometry and behaviour of component 50.

The external skin 50 b is linked to a stress plate 27 with a dissipativecomponent 6.

The continuous or discontinuous, thin, dense stress plate 27 has highmembrane strength and low stiffness in flexion, contrary to the upperskin 50 b.

These differences in modes and deformation amplitude impart high levelsof internal deformation to the dissipative material 6 over the wholetreatment surface thereby ensuring efficient conversion of the vibratoryenergies.

We observe also that specific motifs for component 50, by favouringflexibility in flexion/compression combined with a rigid dense stressplate 27, constitute a “spring-mass” having the intrinsic qualities ofan acoustic screen damping acoustic transmissibility.

The surface device that has just been described, as for all the surfacedevices presented hereafter, judiciously duplicated on the surface whosevibratory response is to be damped, is particularly well adapted to thevibro-acoustic damping of plates of large dimension, for example thinvehicle body sheet metal. To adapt this surface device to the treatmentof curved or warped plates, FIG. 13 proposes a variant of the surfacedevice 7. The lower face 50 a of the structure 50, of anisotropicconformation, is cut along curved lines or curves, secant or not, 53 aand 53 b.

Given the low stiffness in flexion of the stress plate 27 and thedissipative material 6, the assembly 7, during its installation, is ableto adapt itself to the plan or warped geometry of the vibratorystructure 1. Once rigidly linked to this structure 1 using the skin 50a, the device 7 reintegrates all of the characteristics and performancesof the generic concept presented in FIG. 12.

FIGS. 8 and 9 show a “daisy-shaped” surface shape 7 in which, by way ofexample applicable to other shapes, the dissipative material 6 describedpreviously may be formed by viscoelastic, piezoactive, magnetostrictiveor other elements having a function to convert one form of energy intoanother. These elements thus convert vibratory energy into heat,electric, magnetic or other energy.

In this embodiment, a dissipative component 7, shown as a section inFIG. 9, is constituted by an assembly of independent leaf springs 22,joined at their central part. This central part is linked by the rigidinterface 9 to the elastic component 1, or other vibrating structure,whose vibratory response is to be damped. Each spring 22 is providedwith at least one undulation 24 enabling the vibratory movementsperceived at the interface 9 to be amplified in privileged directions.The lower plane surface 26 a at the end of each leaf spring 22 isconnected to the component 1 with a dissipative component 25 a. Theupper plane surface 26 b at the end of each spring 22 is connected to astress plate 27 by another dissipative component 25 b. The stress plateis continuous and thus enables a multitude of “daisy” motifs to beinterconnected via the dissipative component 25, as has been schematisedin FIG. 8.

Thus, the conformation enables all the relative movements of thecomponent 1 to be amplified, seen at the interfaces 9 the plane ends ofthe leaf springs 22 and the stress plate 27. This amplification isdeflected through the dissipative material for efficient energyconversion.

FIGS. 10 and 11 show, by judicious extension and association of thecharacteristics of the damping device, a variant of the filtering anddamping device between an incident surface 9 and a radiating surface 11based on the embodiment shown in FIG. 3. Each cyclically symmetricalmotif is thus constituted by a judicious assembly around a ring 30 ofelastic leaf springs 31 and 32. This assembly integrates a dampingfunction with dissipative materials 33 arranged between the ring 30 andthe spring 31 and dissipative materials 34 arranged between the springs31 and 32, constituting an interface structure. In this case, each ofthe motifs has bases constituting its incident and radiating surfaceswith respect to the surrounding motifs.

Springs 31 and 32 have an evolutive section profile converging towardscentral parts firmly attached to the incident and radiating surfaces,such as the surfaces 9 and 11 shown in FIG. 3. This profile may becontinuous or discontinuous, axisymmetrical or dissymmetrical.

The ring 30 linking springs 31 and 32 enables them to be prestressed,because of their elastic properties, in flexion, traction or torsion,such that under the effect of the weight of the weighty element 36inducing the radiating surface 11, the system is in a resting positionin a functioning zone of low stiffness.

As a whole the geometrical characteristics and the materialsconstituting the springs 31 and 32 combine to intensify thenon-linearity of their behaviour according to the vibratory wave. FIG.11 shows a section in which springs 31 are wound around the ring 30 atone end and joined at the other to delimit the incident surface 9.Similarly, the inner profile of the springs 32 is predisposed to moulditself to the external profile of springs 31 when these reach theirmaximal deformation amplitude. Springs 32 are joined at the other end todelimit the radiating surface 11.

When a dynamic load is transmitted between the incident 8 and radiating11 surfaces, the springs deform according to different pre-establishedmechanisms (flexion, buckling, torsion, traction, . . . ) depending ontheir initial profile and the excitation level and frequency. Thesedifferent types of deformation induce a modification in the stiffness ofthe filtering device.

The natural frequencies of the springs are thus modified therebyenabling the filtering frequencies of the assembly to be controlled andextended.

So as to improve the non-linear dynamic behaviour of the filteringelement, the inner profile of spring 32 has a potential contact surfacewith spring 31 by moulding itself to the form of the maximal admissibledeformation of spring 31. Contact is not established when thedeformation rate of spring 31 is weak. Over a certain threshold, contactis initiated over a small portion of the spring 31. The behaviour of thespring is thus slightly modified. If the dynamic load increases, thecontact surface gradually increases and the dynamic behaviour of thespring 31 is strongly disturbed leading to a significant impact on theincrease in stiffness.

As a whole the deformations of springs 31 and 32 generate relativerotations around the ring 30. The deformation energies are thusdeflected and amplified in this zone. The presence of damping materialsbetween the interfaces of elements 30, 31 and 31, 32 ensures thefunction of converting the energies of vibratory and/or acoustic origininto another form of energy, enabling damping to be integrated into thestructure onto which the device has been mounted.

This particular embodiment may be used to damp vibrations from rotatingmachines or any other vibrating structure. Springs 31 may be connectedto joint means for element 3 by surface 9 and springs 32 and for element2 by surface 11.

It goes without saying that the dimensioning computation tools and meansenable the geometry of the springs and all the dissipative componentsdescribed to be adapted so as to obtain optimal efficiency. The geometryof the spring is established so as to control the different filteringfrequencies required. According to the deformation state of the deviceaccording to the invention (under an applied load), it is understoodthat a suspension configuration with given cut-off frequencies isreplaced by another state in which the cut-off frequencies have beenmodified. When the load is increased, a property of non-linearity issought which enables the amplitude of the motion space or displacementsunder strong load levels to be limited.

1. A process to damp and filter the amplitude of mechanically-originatedvibrations of a structure to be uncoupled, wherein an incident vibratorywave is filtered with damping by absorbing a filtered vibratory wavetransmitted over a frequency and mechanical load amplitude that isapplied to the structure; and a plurality of suspension assemblies areall mounted in series between two elements of the structure with adamping device mounted in parallel to each suspension assembly of saidplurality of suspension assemblies.
 2. The process according to claim 1,wherein the damping device comprises an internal geometry that providesa deflection, and if required, an amplification and location of themechanically-originated vibrations to ensure damping of the vibratoryresponse of the structure, and the series suspension comprises a rigidstatic support function, and a dynamic filtering function with variablecharacteristics based on the level of the load that is applied to thestructure.
 3. A device to filter and damp the vibrations between a firstelement subjected to an incident vibratory wave and a second elementradiating a filtered vibratory wave, wherein the device comprises: aplurality of interface structures all mounted in series between thefirst and second elements, that transfer vibratory energy, each of theplurality of interface structures constituted by (1) at least oneelastic component and (2) at least one dissipative component attached inparallel to the elastic component, to filter and dampen the incidentvibratory wave over a frequency and a mechanical load amplitude that isapplied to each interface structure of said plurality of interfacestructures.
 4. The device according to claim 3, wherein the dissipativecomponent comprises two separate rigid frames that provide deflectionfunctions, if required, by a lever arm effect, wherein amplification ofthe vibratory energies generated by the at least one elastic componenttowards a dissipative material is damped by the dissipative component.5. The device according to claim 3, wherein the dissipative componentcomprises: a linear profile and an assembly of rigid aligned frames,wherein the rigid aligned frames are attached to the at least oneelastic component, or to any other vibrating structure, and areindependent of one another such that the relative movements of eachrigid aligned frame, corresponding to an amplification by lever armeffect of the vibratory response of the elastic component, istransmitted by the end of the rigid aligned frame to a dissipativematerial onto which a stress plate is mounted to transfer the vibratoryenergy to the assembly of rigid aligned frames.
 6. The device accordingto claim 3, wherein the dissipative component comprises: an elementattached to the dissipative component, or to any other vibratingstructure, such that the vibratory waves that are deflected, located andamplified by an internal structure of the device are transmitted, by anupper face of the element to a dissipative material that is stressed onan upper face of the dissipative material by a plate that transfersvibratory energies towards an assembly of rigid frames via thedissipative material.
 7. The device according to claim 3, wherein thedissipative component is rotational and comprises an assembly of rigidframes, spaced cyclically around a central part, attached at one end tothe elastic component, or to any other vibratory structure, andunattached at the another end so that the relative movements of theassembly of rigid frames are transmitted to dissipative materials, andattached at the other end to a stress plate that, through thedissipative materials, retains the assembly of rigid frames.
 8. Thedevice according to claim 3, wherein the elastic component comprises anassembly of two rotational sub-assemblies that are elastic leaf springs,and at least one end of the elastic component has an evolutive contactsurface, wherein the assembly of two rotational sub-assemblies has azone in which the at least one dissipative component is inserted.
 9. Thedevice; according to claim 8, wherein the elastic leaf springs have apotentially non-linear stiffness conferred by an evolutive geometricprofile of the elastic leaf springs to ensure a gradual contact of afirst leaf spring with a matching profile of a second leaf spring, toprovide the evolution of the filtering frequency and a controlledrelative motion space of the leaf springs according to a dynamic loadthat is applied.
 10. The device according to claim 3, wherein theinterface structure is rotational and comprises a first elastic leafspring rigidly connected to the second element and a second elastic leafspring rigidly connected to the first element, the leaf springs beingconnected together at their free ends and wound around a ring, usinglayers of dissipative materials, and coming into direct contactaccording to a dynamic load that is applied to provide a non-linearfiltering and damping function.
 11. The device according to claim 10,wherein the first and second elastic leaf springs have a potentiallynon-linear stiffness to provide, depending on the dynamic load that isapplied, the evolution of the frequency and a controlled relative motionspace of the first and second elements.
 12. The device according toclaim 3, wherein the dissipative material converts vibratory energy intoheat energy by friction between materials or with viscoelasticmaterials, electrical energy with piezoelectric materials, magneticenergy with magnetostrictive materials, or another form of energy.
 13. Afiltering and damping device according to claim 3, wherein the elasticcomponent has at least two dimensions and is formed by assemblies ofbeams, straight or curved bars, solid volumes, plane plates or morecomplex shapes, and elastic properties of the elastic component stemfrom elastic materials that are metallic, homogenous, isotropic oranisotropic.
 14. The device according to claim 6, wherein the elementcomprising the dissipative component of surface profile, integrates theproperties of thermal and acoustic insulation comprising cellular foam,or cork-based composites, enabling the dissipative component to preservedamping efficiency over a wide temperature range and to possess, inaddition, the intrinsic performances of an acoustic screen and thermalinsulator.
 15. The process according to claim 1, wherein the dampingdevice is of the parallel type and has an internal geometry able toprovide a deflection, and if required, an amplification and location ofthe vibrations to ensure damping of the vibratory response of thestructure, and wherein the series suspension concurrently has a rigidstatic support function, and a dynamic filtering function with variablecharacteristics based on the level of the load that is applied to thestructure.
 16. The device according to claim 5, wherein the elasticcomponent has at least two dimensions and is formed by assembliescomprising beams, straight or curved bars, solid volumes, plane platesor more complex shapes, and the elastic component has elastic propertiesthat stem from elastic materials that are metallic, homogeneous,isotropic or anisotropic.
 17. The device according to claim 7, whereinthe elastic component has at least two dimensions and may be formed byassemblies comprising beams, straight or curved bars, solid volumes,plane plates or more complex shapes, and wherein the elastic componenthas properties that stem from elastic materials that are metallic,homogeneous, isotropic or anisotropic.
 18. The device according to claim9, wherein the elastic component has at least two dimensions and may beformed by assemblies comprising beams, straight or curved bars, solidvolumes, plane plates or more complex shapes, and wherein the elasticcomponent has properties that stem from elastic materials that aremetallic, homogeneous, isotropic or anisotropic.
 19. The deviceaccording to claim 11, wherein the elastic component has at least twodimensions and may be formed by assemblies comprising beams, straight orcurved bars, solid volumes, plane plates or more complex shapes, andwherein the elastic component has elastic properties that stem fromelastic materials that are metallic, homogeneous, isotropic oranisotropic.